4 sequential dosing cohorts, each cohort beginning with single dose (SDD), single day exposure, followed by one week of multiple daily dosing (MDD) with bid exposure, a 4 day drug honeymoon, then one week of MDD utilizing tid exposure. Each subsequent cohort utilizes the same SDD/MDD design, starting with SDD higher than prior SDD but a SDD significantly lower than prior tid MDD cohort just completed, the overall goal being to provide gradually increasing dose exposure contingent on satisfactory safety and tolerability of lower doses in the previous groups. Cohort 4 (MDD) utilizes best dose determined by Cohorts 1, 2 & 3 for 21 days.